Integrin α6β4 Controls the Expression of Genes Associated with Cell Motility, Invasion, and Metastasis, Including S100A4/Metastasin

The integrin alpha 6 beta 4 is associated with carcinoma progression by contributing to apoptosis resistance, invasion, and metastasis, due in part to the activation of select transcription factors. To identify genes regulated by the alpha 6 beta 4 integrin, we compared gene expression profiles of MDA-MB-435 cells that stably express integrin alpha 6 beta 4 (MDA/beta 4) and vector-only-transfected cells (MDA/mock) using Affymetrix GeneChip (R) analysis. Our results show that integrin alpha 6 beta 4 altered the expression of 538 genes (p < 0.01). Of these genes, 36 are associated with pathways implicated in cell motility and metastasis, including S100A4/metastasin. S100A4 expression correlated well with integrin alpha 6 beta 4 expression in established cell lines. Suppression of S100A4 by small interference RNA resulted in a reduced capacity of alpha 6 beta 4-expressing cells to invade a reconstituted basement membrane in response to lysophosphatidic acid. Using small interference RNA, promoter analysis, and chromatin immuno-precipitation, we demonstrate that S100A4 is regulated by NFAT5, thus identifying the first target of NFAT5 in cancer. In addition, several genes that are known to be regulated by DNA methylation were up-regulated dramatically by integrin alpha 6 beta 4 expression, including S100A4, FST, PDLIM4, CAPG, and Nkx2.2. Notably, inhibition of DNA methyltransferases stimulated expression of these genes in cells lacking the alpha 6 beta 4 integrin, whereas demethylase inhibitors suppressed expression in alpha 6 beta 4 integrin-expressing cells. Alterations in DNA methylation were confirmed by bisulfate sequencing, thus suggesting that integrin alpha 6 beta 4 signaling can lead to the demethylation of select promoters. In summary, our data suggest that integrin alpha 6 beta 4 confers a motile and invasive phenotype to breast carcinoma cells by regulating proinvasive and prometastatic gene expression.